Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS5384792 A
Publication typeGrant
Application numberUS 08/276,485
Publication dateJan 24, 1995
Filing dateJul 18, 1994
Priority dateMay 14, 1991
Fee statusLapsed
Publication number08276485, 276485, US 5384792 A, US 5384792A, US-A-5384792, US5384792 A, US5384792A
InventorsKatsuya Hirachi
Original AssigneeYuasa Battery Co., Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
For providing power to a load from an AC power source
US 5384792 A
Abstract
An uninterruptible power supply which is down-sized and lightened is provided. A utility line 1 is connected with a switch 8 and the switch 8 is connected with a rectifying circuit 2 and DC power from the rectifying circuit 2 inputs to a first inverter 3-1 and charges a battery 6 by a charger 7 connected with a node between the utility line 1 and the switch 8 and the DC power from the battery 6 is converted to AC power by a second inverter 3-2 to input to the rectifying circuit 2. When the utility line 1 is interrupted, AC power from the second inverter 3-2 is supplied to the rectifying circuit 2 to continuously supply power to a load 4. As a result, the number of cells in a battery may be reduced, the cost and man-day of the unit may be reduced, the reliability of the unit may be improved and the supply may be down-sized and lightened.
Images(2)
Previous page
Next page
Claims(4)
What is claimed is:
1. An uninterruptible power supply for providing power to a load from an AC power source, comprising:
a circuit for rectifying the power from said AC source to generate DC power output having an AC ripple component and operating at a higher frequency than said AC power source;
a switch connecting and disconnecting said AC power source and the rectifying circuit;
a first inverter circuit connected between the DC power output of the rectifying circuit and the load to provide an AC power output thereto, and said AC power output having the same frequency as the AC ripple component of said dc power output of the rectifying circuit;
a battery for providing back-up power to the power supply;
means for charging said battery and connected to said AC power source; and
a second inverter connected to said battery and providing an AC output having the same frequency as said AC power source and connected to the rectifying circuit with said switch disconnecting said AC power source and the rectifying circuit, whereby AC power is supplied continuously to the load.
2. The power supply as claimed in claim 1, wherein the rectifying circuit includes serially-connected first and second switching elements, each said first and second switching element further including a diode connected anti-parallelly therewith, and said switch is connected to the common node of said first and second switching elements.
3. The power supply as claimed in claim 1, wherein said first inverter includes serially-connected third and fourth switching elements, each said switching element further including a diode connected anti-parallelly therewith, said serially-connected third and fourth switching elements being connected in parallel across said first and second serially-connected switching elements.
4. The power supply as claimed in claim 1, wherein said second inverter includes fifth and sixth serially-connected switching elements, seventh and eighth serially-connected switching elements, said serially-connected fifth and sixth switching elements and said serially-connected seventh and eighth switching elements being connected in parallel, and said battery being connected in parallel across the parallelly-connected switching elements.
Description

This application is a file wrapper continuation of application Ser. No. 08/169,549, filed Dec. 20, 1993, now abandoned, which in turn is a file wrapper continuation of application Ser. No. 07/881,210, filed May 11, 1992, also abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an uninterruptible power supply and more particularly to down-sizing and lightening weight of an uninterruptible power supply used as a backup power supply of computers and communication equipment.

2. Description of the Related Art

As shown by block diagrams in FIGS. 3 and 4, an uninterruptible power supply normally supplies AC power from a utility line 1 to a load 4 such as a computer and a communication equipment directly through a direct transmission line 10 or through a rectifying circuit 2 and an inverter 3 and when the utility line is interrupted, supplies DC power from a battery 6 to the load 4 by converting to AC power by the inverter 3 to prevent a trouble of the load 4 caused by the interruption.

The battery 6 in the uninterruptible power supply in FIG. 3 is arranged so that AC power from the utility line 1 is normally converted to DC power by the rectifying circuit 2 and the battery 6 is fully float-charged by the DC power and so that the DC power in the battery 6 is supplied to the inverter 3 when the utility line is interrupted.

On the other hand, a battery 6 in the uninterruptible power supply in FIG. 4 is arranged so that AC power from the utility line 1 is normally supplied to a charger 7 for fully charging the battery 6 and so that a switch 5 is turned on to supply DC power from the battery 6 to the inverter 3 when the utility line is interrupted.

Although the arrangement of the uninterruptible power supply in FIG. 3 may be simplified since the battery 6 is charged by output of the rectifying circuit 2, the output voltage of the rectifying circuit 2 has to adjust the floating charge voltage of the battery 6, so that its accuracy needs to be improved.

On the other hand, although the arrangement of the uninterruptible power supply in FIG. 4 is more complicated than that in FIG. 3, the output voltage of the rectifying circuit 2 may be of the input condition of the inverter 3, so that only the accuracy of the output voltage of the charger 7 needs to be improved.

By the way, the inverter 3 in the uninterruptible power supply as described above is provided with a dead time for preventing its arm from short-circuiting via its switching elements. The switching elements also have forward voltage drops during their ON time. Accordingly, in order to obtain AC 100 V sine wave voltage from the inverter 3, its DC input voltage has to be at least 170 V and the final discharge voltage of the battery 6 also has to be more than 170 V. This means that when a lead-acid battery is used for the battery 6, it needs more than 100 cells.

In order to deal with that, it is tried that a boost-chopper circuit is inserted between the rectifying circuit 2 and the inverter 3, for lowering the output voltage of the rectifying circuit 2, increasing the DC input voltage to the inverter 3 and reducing the number of cells in the battery 6.

Accordingly, such uninterruptible power supply as described above had a disadvantage that the cost of the battery 6 accounts for a large amount in the total cost of the supply due to the large number of cells in the battery 6.

Moreover, since many cells are connected in series in the battery 6, there has been a problem in its reliability and man-day.

Furthermore, although the number of cells in the battery 6 may be reduced by inserting the boost-chopper circuit, such another problems caused by the boost-chopper circuit which is operated in high frequency that the efficiency is lowered, the number of parts is increased, the cost is increased and the reliability is decreased have brought about.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to solve the aforementioned problems by providing an uninterruptible power supply which allows to reduce the number of cells in a battery, to reduce its cost and man-day, to improve its reliability and to down-size and lighten its weight.

In order to achieve the foregoing object, the uninterruptible power supply of the present invention is comprised of a rectifying circuit to which AC power from a utility line is inputted through a switch and which outputs DC power, a first inverter for converting the DC power from the rectifying circuit to AC power, a charger to which AC power from the utility line is inputted and which outputs power for charging a battery, the battery which is charged by the power, and a second inverter for converting DC power from the battery to AC power. Then, when the utility line is interrupted, the AC power from the second inverter is inputted to the rectifying circuit to supply power to a load continuously.

Accordingly, the battery in the present invention is charged by the power from the charger while AC power from utility line is supplied, and its DC power is converted by the second inverter to AC power and inputted to the rectifying circuit when the utility line is interrupted, so that the input voltage to the second inverter may be enough to output AC 100 V since wave through the second inverter, the rectifying circuit and the first inverter and the number of cells in the battery may be reduced.

Moreover, the second inverter needs not be operated in high frequency, so that such problems that the efficiency is lowered and the cost is increased due to the second inverter are eliminated.

The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the description and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an uninterruptible power supply of the present invention;

FIG. 2 is a circuit diagram of the uninterruptible power supply of the present invention;

FIG. 3 is a block diagram illustrating a conventional uninterruptible power supply; and

FIG. 4 is a block diagram illustrating another conventional uninterruptible power supply.

In the foregoing drawings, like reference numerals designate like or corresponding parts throughout several views.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 is a block diagram illustrating an uninterruptible power supply of the present invention and FIG. 2 is a circuit diagram of the uninterruptible power supply of the present invention. The parts having the same functions with those in FIGS. 3 and 4 are denoted by the same reference numerals and explanation thereof is omitted here.

Features of the arrangement of the present invention Lie in that a utility line 1 is connected with a switch 8 and the switch 8 is connected with a rectifying circuit 2 and that DC power from the rectifying circuit 2 inputs to a first inverter 3-1 and charges a battery 6 by a charger 7 connected with a node between the utility line 1 and the switch 8 and that DC power from the battery is converted to AC power by a second inverter 3-2 to input to the rectifying circuit 2.

While AC power from the utility line 1 is supplied, the AC power is inputted to a load 4 by turning the switch 8 on and through the rectifying circuit 2 and the first inverter 3-1 or by a direct transmission line 10 and the battery 6 is charged by the charger 7. By the way, it may be needless to say that the operation of the second inverter 3-2 is stopped during this time to prevent unnecessary discharge of the battery 6.

When the utility line 1 is interrupted, the second inverter 3-2 starts its operation, its AC power is inputted to the rectifying circuit 2 to convert to DC power and the DC power is converted to AC power by the first inverter 3-1 and continuously supplied to the load 4. The power of the battery 6 may be effectively utilized during the interruption by turning off the switch 8 not to supply the AC power from the second inverter 3-2 backwardly to the utility line 1 and the direct transmission line 10.

Referring now to FIG. 2, one embodiment of the uninterruptible power supply of the present invention will be explained.

In FIG. 2, the rectifying circuit 2 is comprised of switching elements T1 and T2 connected in series and diodes D1 and D2 connected with each element in anti-parallel, the first inverter 3-1 is comprised of switching elements T3 and T4 connected in series and diodes D3 and D4 connected with each element in anti-parallel and the second inverter 3-2 is comprised of two sets of switching elements T5, T6 and T7, T8 respectively connected in series. A choke coil L1 is inserted between the switch 8 and the rectifying circuit 2, capacitors C1 and C2 connected in series are inserted between the rectifying circuit 2 and the first inverter 3-1 and a filter circuit 9 is inserted between the first inverter 3-1 and the load 4.

While AC power from the utility line 1 is supplied, the switching element T2 is turned on and the current from the utility line 1 flows through the choke coil L1, the switching element T2, the capacitor C2 during its positive half cycle. Sum of the voltage of the utility line 1 and that of the capacitor C2 is applied to the choke coil L1 and the current gradually increases, storing energy in the choke coil L1. Then when the switching element T2 is turned off, the energy stored in the choke coil L1 is transferred to the capacitor C1 from the choke coil L1 through the diode D1, the capacitor C1 and the utility line 1. Since the voltage of the capacitor C1 is applied to the choke coil L1, its current gradually decreases. In this half cycle, the switching element T1 is turned off and only the switching element T2 repeats the aforementioned operations in high frequency.

While AC power from the utility line 1 is supplied, the switching element T1 is turned on and the current from the utility line 1 flows through the capacitor C1, the switching element T1, the choke coil L1 during its negative half cycle. Sum of the voltage of the utility line 1 and that of the capacitor C1 is applied to the choke coil L1 and the current gradually increases, storing energy in the choke coil L1. Then when the switching element T1 is turned off, the energy stored in the choke coil L1 is transferred to the capacitor C2 from the choke coil L1 through the utility line 1, the capacitor C2 and the diode D2. Since the voltage of the capacitor C2 is applied to the choke coil L1, its current gradually decreases. In this half cycle, the switching element T2 is turned off and only the switching element T1 repeats the aforementioned operations in high frequency.

Accordingly, by controlling ON and OFF ratio of the switching elements T2 and T1 in each positive and negative cycle, waveform of AC input current may be turned into sine wave by the rectifying circuit 2 and the power factor may rise. Moreover, its DC output voltage may be controlled to be constant voltage by controlling amplitude of the AC input current.

The DC power thus obtained is supplied to the first inverter 3-1 and its sine wave output may be supplied to the load 4. The positive half cycle output is obtained by turning the switching element T3 on and off in high frequency having pulse width that corresponds to the amplitude of the sine wave output and the negative half cycle output is obtained by turning the switching element T4 in high frequency having pulse width that corresponds to the amplitude of the sine wave output.

While AC power from the utility line 1 is supplied, the battery 6 is charged by the charger 7, but the operation of the second inverter 3-2 is stopped to prevent the battery 6 from discharging unnecessarily.

On the other hand, when the utility line 1 is interrupted, the switch 8 is turned off and the second inverter 3-2 starts its operation. The second inverter 3-2 derives rectangular wave output of commercial frequency and the output of the positive half cycle derives by turning the switching elements T5 and T8 on continuously and the output of the negative half cycle derives by turning the switching elements T6 and T7 on continuously.

Accordingly, the waveform of the AC voltage supplied to the rectifying circuit 2 during the utility line is interrupted is changed from sine wave to rectangular wave and the input current also changes from sine wave to rectangular wave, but the rectifying circuit 2 and the first inverter 3-1 operate in the same way. At this time, the voltage of the rectangular wave becomes equal to the voltage of the battery 6, but since the rectifying circuit 2 has a boosting effect, AC 100 V sine wave voltage may be obtained from the first inverter 3-1 without raising its input voltage. This means that the number of cells in the battery 6 may be reduced.

Moreover, since the second inverter 3-2 derives rectangular output of the commercial frequency, the switching elements T5, T6, T7 and T8 may be of what having low switching speed and therefore, the cost may be reduced and the efficiency of the supply will not be lowered due to switching loss.

As described above, according to the present invention, the number of cells in the battery 6 may be reduced, so that the cost of the battery 6 may be reduced and it is advantageous in terms of the man-day and the reliability of the supply.

Furthermore, since the number of cells of the battery 6 may be reduced according to the present invention, the supply may be down-sized and its weight may be lightened.

Still more, since the second inverter 3-2 is operated by commercial frequency, the cost will not be increased due to parts to be used and almost no decrease of the efficiency of the supply will be brought about due to the second inverter 3-2.

While the described embodiment represents the preferred form of the present invention, it is to be understood that modifications will occur to those skilled in the art without departing from the spirit of the invention. The scope of the invention is therefore to be determined solely by the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4313060 *Feb 15, 1980Jan 26, 1982Bell Telephone Laboratories, IncorporatedUninterruptible power supply with load regulation of standby voltage source
US4673825 *Feb 15, 1985Jun 16, 1987Exide Electronics CorporationUninterruptible power supply with isolated bypass winding
US4707618 *Jun 2, 1986Nov 17, 1987Haas Richard MFor maintaining continuous flow of power to a load
US4719550 *Sep 11, 1986Jan 12, 1988Liebert CorporationUninterruptible power supply with energy conversion and enhancement
US4782241 *Aug 11, 1987Nov 1, 1988Liebert CorporationUninterruptible power supply apparatus and power path transfer method
US4827150 *Jun 8, 1988May 2, 1989Reynal Thomas JUninterruptible power supply inverter circuit
US4868832 *Feb 8, 1988Sep 19, 1989Marrington S PaulComputer power system
US5045989 *Sep 6, 1989Sep 3, 1991Kabushiki Kaisha ToshibaPWM power supply eliminating modulation-frequency components from ground potentials
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5585677 *Dec 30, 1994Dec 17, 1996Samsung Electronics Co., Ltd.Backup power-supply system for emergency
US5684686 *Jun 7, 1995Nov 4, 1997Deltec Electronics CorporationBoost-input backed-up uninterruptible power supply
US5751564 *Aug 10, 1994May 12, 1998Dien; Ghing-HsinDual/multiple voltage level input switching power supply
US5777398 *Dec 8, 1994Jul 7, 1998Compower OyInternal backup power device for a computer
US5834858 *Jun 10, 1996Nov 10, 1998Electronic Design & Manufacturing Inc.Emergency power supply
US5929538 *Jun 27, 1997Jul 27, 1999Abacus Controls Inc.For delivering power to a load
US5982652 *Jul 14, 1998Nov 9, 1999American Power ConversionMethod and apparatus for providing uninterruptible power using a power controller and a redundant power controller
US5994794 *May 9, 1997Nov 30, 1999Active Power, Inc.Methods and apparatus for providing protection to batteries in an uninterruptible power supply
US6201319Aug 26, 1999Mar 13, 2001American Power ConversionUninterruptible power supply
US6240337 *Apr 2, 1998May 29, 2001Bell Atlantic Network Services, Inc.Flywheel reserve power for outside plant of a communication network
US6295215Apr 6, 2000Sep 25, 2001Powerware CorporationAC power supply apparatus with economy mode and methods of operation thereof
US6304006Dec 28, 2000Oct 16, 2001Abb T&D Technology Ltd.Energy management uninterruptible power supply system
US6388852Feb 7, 2000May 14, 2002Gerry BobashFlicker protection circuit
US6483206 *Feb 10, 1999Nov 19, 2002France TelecomElectric power supply system for simplifying the architecture of power and air-conditioning installations
US6744648 *Aug 5, 2002Jun 1, 2004Digi Power Manufacturing Inc.Active backup power supply with power factor correction and output voltage regulation
US6906933Nov 1, 2002Jun 14, 2005Powerware CorporationPower supply apparatus and methods with power-factor correcting bypass mode
US6967283Jan 2, 2002Nov 22, 2005American Power Conversion CorporationAdjustable scalable rack power system and method
US6992247Oct 31, 2002Jan 31, 2006American Power Conversion CorporationToolless mounting system and method for an adjustable scalable rack power system
US7239043May 26, 2004Jul 3, 2007Eaton Power Quality CorporationPower conversion apparatus and methods using an adaptive waveform reference
US7358439Nov 10, 2005Apr 15, 2008American Power Conversion CorporationAdjustable scalable rack power system and method
US7362007 *May 24, 2006Apr 22, 2008Walter Emory FarmerHybrid uninterruptible power supply system
US7379305Jan 23, 2004May 27, 2008American Power Conversion CorporationModular UPS
US7425682Apr 13, 2005Sep 16, 2008American Power Conversion CorporationToolless mounting system and method for an adjustable scalable rack power system
US7446433Jan 23, 2004Nov 4, 2008American Power Conversion CorporationMethods and apparatus for providing uninterruptible power
US7606014Jun 16, 2006Oct 20, 2009American Power Conversion CorporationApparatus and method for scalable power distribution
US7612472Jan 23, 2004Nov 3, 2009American Power Conversion CorporationMethod and apparatus for monitoring energy storage devices
US7615890Oct 23, 2007Nov 10, 2009American Power Conversion CorporationMethods and apparatus for providing uninterruptible power
US7619868Jun 21, 2007Nov 17, 2009American Power Conversion CorporationApparatus and method for scalable power distribution
US7675740Mar 7, 2008Mar 9, 2010American Power Conversion CorporationAdjustable scalable rack power system and method
US7718889Feb 10, 2004May 18, 2010American Power Conversion CorporationAdjustable scalable rack power system and method
US7737580Aug 31, 2004Jun 15, 2010American Power Conversion CorporationMethod and apparatus for providing uninterruptible power
US7855472May 19, 2010Dec 21, 2010American Power Conversion CorporationMethod and apparatus for providing uninterruptible power
US7855872Mar 7, 2008Dec 21, 2010American Power Conversion CorporationToolless mounting system and method for an adjustable scalable rack power system
US7911088Nov 2, 2009Mar 22, 2011American Power Conversion CorporationMethod and apparatus for monitoring energy storage devices
US7940504Oct 1, 2009May 10, 2011American Power Conversion CorporationApparatus and method for scalable power distribution
US8027134Sep 10, 2009Sep 27, 2011American Power Conversion CorporationApparatus and method for scalable power distribution
US8053927Dec 15, 2010Nov 8, 2011American Power Conversion CorporationMethod and apparatus for providing uninterruptible power
US8107225Mar 8, 2010Jan 31, 2012American Power Conversion CorporationAdjustable scalable rack power system and method
US8148846Nov 6, 2009Apr 3, 2012American Power Conversion CorporationMethods and apparatus for providing uninterruptible power
US8162417May 19, 2008Apr 24, 2012American Power Conversion CorporationModular UPS
US8173898May 13, 2010May 8, 2012American Power Conversion CorporationAdjustable scalable rack power system and method
US8212427Dec 3, 2009Jul 3, 2012American Power Converison CorporationApparatus and method for scalable power distribution
US8503149May 9, 2011Aug 6, 2013Schneider Electric It CorporationApparatus and method for scalable power distribution
US8604640Apr 2, 2012Dec 10, 2013Schneider Electric It CorporationMethods and apparatus for providing uninterruptible power
US8610316Jul 2, 2012Dec 17, 2013Schneider Electric It CorporationApparatus and method for scalable power distribution
US8698354Nov 5, 2010Apr 15, 2014Schneider Electric It CorporationSystem and method for bidirectional DC-AC power conversion
US8723358Jun 30, 2011May 13, 2014Vycon, Inc.Line interactive power quality system
US8803361Jan 19, 2011Aug 12, 2014Schneider Electric It CorporationApparatus and method for providing uninterruptible power
US20120069512 *Oct 29, 2010Mar 22, 2012Hon Hai Precision Industry Co., Ltd.Power supply system and container data center including same
EP1952502A1 *Oct 24, 2006Aug 6, 2008VRB Power Systems, Inc.Telecommunication system incorporating a vanadium redox battery energy storage system
EP1965487A1 *Feb 28, 2007Sep 3, 2008Gamesa Innovation & Technology, S.L.Uninterruptible power supply, connected to a grid
EP2276144A2 *Oct 24, 2006Jan 19, 2011JD Holding IncTelecommunication system incorporating a vanadium redox battery energy storage system
WO2006128008A2 *May 24, 2006Nov 30, 2006Emory Farmer FarmerHybrid uninterruptible power supply system
Classifications
U.S. Classification714/14, 714/E11.083, 307/64
International ClassificationH02J9/06, G06F11/20
Cooperative ClassificationH02J9/062, G06F11/2015
European ClassificationH02J9/06C, G06F11/20K
Legal Events
DateCodeEventDescription
Mar 25, 2003FPExpired due to failure to pay maintenance fee
Effective date: 20030124
Jan 24, 2003LAPSLapse for failure to pay maintenance fees
Aug 13, 2002REMIMaintenance fee reminder mailed
Jul 13, 1998FPAYFee payment
Year of fee payment: 4
Oct 13, 1994ASAssignment
Owner name: YUASA BATTERY CO., LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HIRACHI, KATSUYA;REEL/FRAME:007165/0788
Effective date: 19920508